The present invention relates to a lighting device with an illuminated front panel, with a plurality of light-emitting diodes (LEDs) serving as the light source, each LED including a bulb that fits over the LED, converting the light emitted from the LED into light of a desired hue.
For example, such a lighting device could be used as a channel letter, which is commonly constructed of an enclosure that outlines the desired shape, such as the shape of a letter or other alphanumeric character. The enclosure has a substantially flat rear surface for attachment to a building, and more importantly, is designed to house a light source such as an incandescent lamp, fluorescent lighting, or neon lighting. Finally, the front of the enclosure is open for receiving a substantially translucent lens. The lens is commonly tinted and diffuses light emanating from the light source, at least to some extent, and thus provides an illuminated letter or other shape.
For another example, such a lighting device could be used as a “light box” for illuminating a translucent, printed sheet. Specifically, like the above-described channel letter, such a light box is constructed of an enclosure. The enclosure has a substantially flat rear surface for attachment to a wall surface and is designed to house a light source such as an incandescent lamp, fluorescent lighting, or neon lighting. The front of the enclosure is open for receiving a substantially translucent panel, which serves to scatter and diffuse light emitted from the light source. The printed sheet is then secured to the front of the panel and is illuminated. Such a light box may be used in gaming machines, where a printed sheet of graphics is secured to the front of the panel of the light box. Such a light box may also be used for movie posters, with the movie poster secured to the front of the panel of the light box.
As mentioned above, the light sources typically used in constructing such a channel letter or a light box, such as fluorescent lighting or neon lighting, provide uniform and bright light typically devoid of hot spots; however, they have a variety of shortcomings. For example, such light sources often have a relatively short life, operate at high voltages, consume large amounts of energy, and/or are fragile. Additionally, with regard to neon lighting, it is both fragile and heavy, primarily due to its supporting infrastructure, making it expensive to package or ship. Moreover, it is extremely awkward to initially handle, install, and/or replace neon lighting.
LEDs have shown great promise to those interested in alternate light sources for various lighting products. LEDs are not only lightweight and resilient, but, when compared to other light sources, have a long life, operate at low voltages, and consume small amounts of energy. Thus, LEDs are now commonly used for a wide variety of general illumination and special effects illumination. For example, commonly assigned U.S. Pat. Nos. 6,592,238; 6,953,262; and 7,188,970, which are incorporated in their entirety herein by this reference, each describe an illumination device for simulating neon lighting having a plurality of spaced LEDs positioned adjacent the light-receiving surface of a rod-like member or waveguide. The rod-like member/waveguide is made of a material that preferentially scatters light entering the light-receiving surface such that the light intensity pattern exiting a light-emitting surface of the rod-like member/waveguide is substantially uniform.
However, the available visible color spectrum for illumination devices that use LEDs is limited by the finite availability of LED colors. Therefore, in commonly assigned U.S. Pat. Nos. 7,011,421; 7,264,366; and 7,264,367, each of which is also incorporated herein by this reference, illumination devices are described that use LEDs in conjunction with fluorescent and/or phosphorescent dyes, allowing for the emission of light in hues that cannot ordinarily be achieved through the use of LEDs alone.